Novel hard rock breaking technique using ultra-high-frequency particle impact induced by ultrasonic vibration field

With the gradual increase in drilling and mining depth in geothermal, oil, and other fossil energy explorations, complex geological environments (especially hard strata) have forced researchers to develop high-efficiency rock-breaking techniques. Inspired by the dynamic impact theory and the particle jet technique, an ultrasonic vibration field-induced ultra-high-frequency particle impact rock-breaking (UPIRB) technique was proposed to solve these problems. After being subjected to ultrasonic vibration, the small-sized particles generate ultra-high frequency and high impact stress on the rock sample, which can significantly promote rock degradation and improve rock-breaking efficiency. A comparative study between UPIRB and traditional ultrasonic vibration rock-breaking (UVRB) techniques in terms of rock-breaking efficiency was conducted using a series of physical experiments and two-dimensional discrete element numerical simulations. The results showed that owing to the small contact area due to small size particles, UPIRB has incomparable advantages compared with traditional UVRB: its impact stress level is improved by more than ten times, the rock-breaking time is shortened from minutes (2–3 min) to seconds (2–4 s), and the rock-breaking efficiency is improved nearly ten-fold, overcoming the disadvantages of UVRB. This study proposed a novel and efficient rock-breaking technique for energy exploration engineering.